The present invention relates to an absorptive structure or absorbent pad such as diapers, sanitary napkins, bed pads, incontinent pads, towels, bandages, and the like, and more particularly to absorptive structures or pads which freely allow fluids to pass into the interior of an absorptive device but which inhibit the reversal of the fluid. Such absorptive structures generally consist basically of a permeable top sheet, an absorptive element and a back sheet.
Presently, many absorbent pads such as baby diapers are made with a non-permeable sheet, i.e. non-permeable to the fluids being absorbed by the pad, an absorbent material and a permeable sheet. For ease in manufacture, the absorbent material has a carrier sheet on one or more sides thereof and the carrier material will not seal to either the permeable or impermeable sheet without some type of adhesive application during production.
Various types of fluid permeable top sheets have been constructed. For example, U.S. Pat. No. 3,814,107 issued to Kozak on June 4, 1974 illustrates a top sheet of a non-fibrous hydrophobic film which is provided with a plurality of valvular slits which restrict the reverse flow of liquid from the absorbent element of the device. U.S. Pat. No. 3,929,135 issued to Thompson on Dec. 30, 1975 describes a permeable top sheet which is provided with tapered capillaries of a particular pyramidal construction. Various degrees of success have been obtained with these prior art constructions.
It is therefore an important object of the present invention to provide an absorbent structure made of materials that will seal without the necessity of adding an adhesive during the production of the absorbent structure.